Conclusion

So, how did it end up looking? Here's a short video:

As usual, the code is freely downloadable and the parts
I wrote are licensed under the GPLv3. If you use it to create something, I'd like a
heads-up. If you manage to get the portal sending stuff to the Nether in this multiplayer world, I'd
really appreciate a patch, hehe.

Many thanks to Claude Schwarz, both for telling me about the E66 display as wel as giving me
the STM32s I used, J63 who helped me obtain the displays I used and ofcourse Notch
and crew for creating Minecraft in the first place.